Turtle Farmer

-- farmer by shaolin
-- store it to startup file

fuelLevelToRefuelAt = 10

function main()
  print("-------------------------")
  print("--- farmer by shaolin ---")
  print("-------------------------")
  print("---  redstone on back ---")
  print("---    fuel on top    ---")
  print("---  result on down   ---")
  print("-------------------------")
  while turtle.getItemCount(1) < 1 do
    print("Place seed in 1st slot, and press enter...")
    io.read()
  end
  searchStartPosition()
  while (true) do
    waitSignal()
    if chargeInventory() then
      processFarming()
      searchStartPosition()
      chargeInventory()
    end
  end
end


function chargeInventory()
  turtle.select(16)
  turtle.suckUp()
  if turtle.getItemCount(16) < 2 then
    print("Fill the fuel chest and try again!")
    return false
  end
  for i=2,15 do
    turtle.select(i)
    if turtle.compareTo(16) then
      turtle.dropUp()
    else
      if turtle.compareTo(1) then
         turtle.transferTo(1)
         if (i > 2) then
           turtle.transferTo(2) -- store seeds in 1,2 slots
         end
         turtle.dropDown()
      else
         turtle.dropDown()
      end
    end
    while (i > 2) and turtle.getItemCount(i) > 0 do
      print("Chest is full, empty it and press enter..")
      io.read()
      turtle.dropDown()
    end
  end
  return true
end

function selectSeedSlot()
  turtle.select(1)
  for i=2,15 do
    if turtle.compareTo(i) then
      turtle.select(i)
      return true
    end
  end
  return turtle.getItemCount(1) > 2
end

function dig()
       if not turtle.detectUp() then
          turtle.select(2)
          turtle.digDown()
          turtle.suckDown()
          if selectSeedSlot() then
            if not turtle.placeDown() then
               turtle.digDown()  -- hoe
               turtle.placeDown()
            end
          end
        end
end

function processFarming()
  turtle.turnLeft()
  while not turtle.detect() do
    ensureFuel()
    forwardToKill()
  end
  turtle.turnRight() --left bottom pos of field
  print("Start farming...")
  fin = false
  while not fin do
    for i = 1,2 do
      while not turtle.detect() do
        ensureFuel()
        dig()
        turtle.forward()
      end
      if i==1 then
        turtle.turnRight()
        if turtle.detect() then
          fin = true
        else
          dig()
          turtle.forward()
        end
        turtle.turnRight()
      else
        turtle.turnLeft()
        if turtle.detect() then
          fin = true
        else
          dig()
          turtle.forward()
        end
        turtle.turnLeft()
      end
    end
  end
  dig()
  print("... complete!")
end

function waitSignal()
  print("Waiting for signal...")
  while not redstone.getInput("back") do
    os.sleep(1)
  end
  print("... got it!")
end

function searchStartPosition()
  print("Finding start position...")
  if turtle.detectUp() and turtle.detect() then
    turtle.turnRight()
    turtle.turnRight()
  end
  if turtle.detectUp() then
    print("... already!")
    return true
  end
  while not turtle.detectUp() do
    ensureFuel()
    i = 0
    while turtle.detect() do
      turtle.turnRight()
      i = i + 1
      if i > 4 then
        print("I'm lost! where I am? fix and [enter]")
        io.read()
      end
    end
    forwardToKill()
  end
  turtle.turnRight()
  print("... found!")
end

function forwardToKill()
    i = 0
    while (not turtle.forward()) and (i < 20) do
      print("Somebody on my farm!")
      turtle.attack()
      i = i + 1
    end
end

--Check fuel, refueling from inventory special slot or not
function ensureFuel()
  -- Determine whether a refuel is required
  local fuelLevel = turtle.getFuelLevel()
  if (fuelLevel ~= "unlimited") then
    if (fuelLevel < fuelLevelToRefuelAt) then
      -- Need to refuel
      turtle.select(16)
      local fuelItems = turtle.getItemCount(16)
      -- Do we need to impact the emergency fuel to continue? (always
      -- keep one fuel item in slot 16)
      if (fuelItems == 0) then
        print("I want more fuel!")
        io.read()
      elseif (fuelItems == 1) then
        --load fuel from another slot
    local fueled = false
    local fromSlot = 2
        for i=fromSlot,15,1 do
          turtle.select(i)
      if (turtle.refuel(0)) then  -- I can eat that
        print("Refueling from not fuel slot: "+i)
        turtle.refuel(1)
        turtle.transferTo(16)
        fueled = true
          end
        end
        if not fueled then
          print("completely out of fuel!")
        end
      else --fuelItems > 1
        print("Time to refueling!")
        turtle.refuel(1)
      end
    end
  end
end

main()